What is the best way to trim() in javascript

Question

The question says it all; JS doesn't seem to have a native trim() method.

Answer 1

The shortest form for jQuery:

string = $.trim(string);

Link

Answer 2

according to this page the best all-around approach is

return str.replace(/^\s\s*/, '').replace(/\s\s*$/, '');

Of course if you are using jQuery , it will provide you with an optimized trim method.

Answer 3

I know this question is ancient but now, Javascript actually does have a native .trim()

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim

Answer 4

Well, as a lot of people always says, the trim function works pretty well, but if you don't want to use a whole framework just to perform a trim, it may be useful to take a look at its implementation. So here it is:

function( text ) { return (text || "").replace( /^(\s|\u00A0)+|(\s|\u00A0)+$/g, "" );}

The main advantages I see in this implementation, comparing to other solution already proposed here are:

• The 'g' flag that allows you to perfom a trim on a multi-line string
• The (text || "") syntax that ensure that the function will always work, even if the argument passed is null or undefined.

Answer 5

As a couple of others have already noted, it's usually best to do this sort of thing by using a third-party JS library. Not that trim() is a complicated function to build yourself, but there are so many functions that aren't native to JavaScript that you might need and end-up writing yourself, it soon becomes more cost-effective to use a library.

Of course, another advantage of using a JS library is that the authors do the hard work of ensuring that the functions work across all the major browsers, so that you can code to a standard interface and forget about the irritating differences between Internet Explorer and all the other browsers.

Answer 6

@Pat的略微版本。

return str.replace( /^\s+|\s+$/g, '' );

Answer 7

For ltrim, replace spaces anchored at the start of the string with nothing:

str2 = str.replace(/^\s+/,'');

For rtrim, replace spaces anchored at the end of the string with nothing:

str2 = str.replace(/\s+$/,'');

For trim:

str2 = str.replace(/^\s+|\s+$/g,'');

These all use regex'es to do the actual work.

Answer 8

Use Ariel Flesler's fast trim function :

// Licensed under BSD
function myBestTrim( str ){
 var start = -1,
  end = str.length;
 while( str.charCodeAt(--end) < 33 );
 while( str.charCodeAt(++start) < 33 );
 return str.slice( start, end + 1 );
};

My solution, though, would be this (because the String object in Firefox 3.5 and above already has a trim method ):

String.prototype.trim = String.prototype.trim || function () {
    var start = -1,
        end   = this.length;

    while( this.charCodeAt(--end) < 33 );
    while( this.charCodeAt(++start) < 33 );

    return this.slice( start, end + 1 );
};

Answer 9

Why not just modify the String prototype? Why not steal the trim function from an open source library, like I did here with YUI? (Do you really need to load and entire framework for this simple taks?) Put them together and you get this:

String.prototype.trim = function() {
    try {
        return this.replace(/^\s+|\s+$/g, "");
    } catch(e) {
        return this;
    }
}

var s = " hello ";
alert(s.trim() == "hello"); // displays true

Answer 10

I made a trim-function speed in mind. This function beats in a clear difference all of 24 competitors (of which many use regular expressions) and also native string.trim() of Chrome and Chromium(!) and performs as speedy as Safari's trim(). Test results are here: http://jsperf.com/mega-trim-test/7

function trim27(str) {
  var c;
  for (var i = 0; i < str.length; i++) {
    c = str.charCodeAt(i);
    if (c == 32 || c == 10 || c == 13 || c == 9 || c == 12)
    continue; else break;
  }
  for (var j = str.length - 1; j >= i; j--) {
    c = str.charCodeAt(j);
    if (c == 32 || c == 10 || c == 13 || c == 9 || c == 12)
    continue; else break;
  }
  return str.substring(i, j + 1);
}

The function trims characters " \\n\\r\\t\\f", but it's easy to add more whitespace-characters, eg. those that regexp uses as whitespaces (\\s) with only a minor performance lost ( please see http://jsperf.com/mega-trim-test/8 ).

Edit: The previous trim27() trims only the most common characters (" \\n\\r\\t\\f"), but to trim all possible whitespaces, I included below a new function mytrim():

if (!String.prototype.trim || "\x09\x0A\x0B\x0C\x0D\x20\xA0\u1680\u180E\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200A\u202F\u205F\u3000\u2028\u2029\uFEFF".trim() || navigator.userAgent.toString().toLowerCase().indexOf("chrome") != -1)
    var mytrim = function(str) {
        var c;
        for (var i = 0; i < str.length; i++) {
            c = str.charCodeAt(i);
            if (c == 32 || c == 10 || c == 13 || c == 9 || c == 12 || c == 11 || c == 160 || c == 5760 || c == 6158 || c == 8192 || c == 8193 || c == 8194 || c == 8195 || c == 8196 || c == 8197 || c == 8198 || c == 8199 || c == 8200 || c == 8201 || c == 8202 || c == 8232 || c == 8233 || c == 8239 || c == 8287 || c == 12288 || c == 65279)
            continue; else break;
        }
        for (var j = str.length - 1; j >= i; j--) {
            c = str.charCodeAt(j);
            if (c == 32 || c == 10 || c == 13 || c == 9 || c == 12 || c == 11 || c == 160 || c == 5760 || c == 6158 || c == 8192 || c == 8193 || c == 8194 || c == 8195 || c == 8196 || c == 8197 || c == 8198 || c == 8199 || c == 8200 || c == 8201 || c == 8202 || c == 8232 || c == 8233 || c == 8239 || c == 8287 || c == 12288 || c == 65279)
            continue; else break;
        }
        return str.substring(i, j + 1);
    };
    else var mytrim = function(str) {
        return str.trim();
    }

Use it this way:

var foo = mytrim(" \n \t Trimmed \f \n "); // foo is now "Trimmed"

The above mytrim() does the following:

• Trims 26 different whitespaces (all of 25 whitespaces mentioned in http://perfectionkills.com/whitespace-deviations/ and additionally uFEFF, which is ZERO WIDTH NO-BREAK SPACE.
• Makes trimming results consistent across browsers.
• Uses native trim() if it is available AND has ability to trim all of 27 different whitespaces. The exception is Chrome and Chromium which both have so slow native trim() that instead of native we use our custom trim.
• AND THE MOST IMPORTANT: Is not beautiful and is not short, but IS CLEARLY FASTER than any of the 24 competitive alternatives in http://jsperf.com/mega-trim-test/12 (exception: rather old Firefox 3.6.25 in Windows 7 runs mytrim() rather slowly for unknown reason).

Answer 11

I use this with native JavaScript

// Adding trim function to String object if its not there
if(typeof String.prototype.trim !== 'function') {
  String.prototype.trim = function() {
    return this.replace(/^\s+|\s+$/g, '');
  }
}

Use like this

var myString = "                  some text                  ";

alert(myString.trim());

Example

 // Adding trim function to String object if its not there if(typeof String.prototype.trim !== 'function') { String.prototype.trim = function() { return this.replace(/^\\s+|\\s+$/g, ''); } } var str = " some text "; console.log(str.trim()); 

Answer 12

I use this.

    String.prototype.trim = function() {
        return this.replace(/^\s+|\s+$/g,"");
    }

Answer 13

The answer to so many JavaScript questions: jQuery

$j.trim(string)

Note: the above assumes your jQuery has been setup with:

<script type="text/javascript">$j = jQuery.noConflict();</script>

Which is far more sensible than "$", and far less verbose than typing "jQuery" every time.

Answer 14

Microsoft .NET also has String.trim function as a part of JavaScript Base Type Extensions. It could be used if you are coding ASP.NET application.

Answer 15

This is probably not the fastest, and might violate what ".trim()" probably should really be, but I don't like RegExs (mainly because it takes so much time to figure out what they really mean/do) and I like having something that I know will work regardless of whether I have jQuery or not (not to mention the right version, since I tried $.trim(myVar) with jQuery 1.4.2 and it does not work), and will get rid of ALL extra spaces, not just at the end, rebuilding it like it should be:

function Trim(obj) {
    var coll = "";
    var arrObj = obj.split(' ');

    for (var i=0;i<arrObj.length;i++) {
        if (arrObj[i] == "") {
            arrObj.splice(i,1);  // removes array indices containing spaces
        }
    }
    //alert(arrObj.length);  // should be equal to the number of words
    // Rebuilds with spaces in-between words, but without spaces at the end
    for (var i=0;i<arrObj.length;i++) {
        if (arrObj[i] != "" && i != arrObj.length-1)
            coll += arrObj[i] + " ";
        if (arrObj[i] != "" && i == arrObj.length-1)
            coll += arrObj[i];
    }

    return coll;
}

Answer 16

Actually, with jQuery this seems to be the way:

jQuery.trim(string)

(Reference)

Answer 17

This is an old question but none of these worked for me. I just needed to trim leading and trailing white space and this is what I did. My div tag had an id = start-date.

$("#start-date").text().trim()

Answer 18

I use this:

Work with functions.

 function trim($) { 
                return (typeof $ == "function" ? $() : $).replace(/[\s]*/g,"")
        }

        code example: 

        trim((function(){ return "a  b"})) // ab

        trim(" a  b") //ab

Answer 19

You can use following ...

function trim(str) {
    try {
        if (str && typeof(str) == 'string') {
            return str.replace(/^\s*|\s*$/g, "");
        } else {
            return '';
        }
    } catch (e) {
        return str;
    }
}